If you've been to the movies in the past five years, you've seen a lot of these 10 stars.

Four feature films, one animated feature and one short film. It'd be a spectacular year for any actor, but 2008 was pretty average for Samuel L. Jackson, one of the hardest-working actors in Hollywood.

"There's something to be said for the Christopher Walken school of acting, where you just take project after project after project," says Jeff Bock, box-office analyst for Exhibitor Relations. For Jackson, it's a strategy that's made him one of the most recognizable stars in the world.

What other A-list actors are working as hard? We decided to find out. We looked at all movies released since January 2005 that earned more than $20 million at the U.S. box office (439 films in total). From there we tallied which actors had the most starring or significant supporting roles during that period. Ties were broken by cumulative box-office totals.

The list ranks how hard an actor works not only in terms of output but with the financial consideration of box-office earnings; it measures how effective the actor's work is for the bottom line of the studios and the theater operators. It continues a constant debate: Is an A-list star worth the cost? Sometimes even the biggest stars attached to the largest megaplex vehicles fail to recoup the projected returns, leaving the studio to redeem outlays from a long tail of foreign, DVD and cable returns.

No. 1 on our ranking of Hollywood's hardest-working actors: Morgan Freeman. Now known to many as Lucius Fox, the unmasked man behind Wayne Enterprises in the latest screen versions of the Batman epic, Freeman has been in nine films that grossed more than $20 million since 2005, including "The Bucket List," "Evan Almighty" and "Lucky Number Slevin."

Directly behind Freeman is Seth Rogen. With eight films earning at least 20 million box-office bucks, he's the hardest-working comedic actor on our list. His films earned a total of $1.2 billion, more than any other star on the ranking. Since his frontman debut with "The 40-Year-Old Virgin" in 2007, he's become Judd Apatow's go-to goof with roles in "Knocked Up" and "Superbad."

"When you've created a persona and there's an appetite for it, that's an appetite you want to feed as long as people have it," says Robert Thompson, pop culture expert and Syracuse University professor. "If it disappears for too long, the character begins to fade away from the high-voltage territory of popular culture."

Going beyond the character type for which an actor is known is a familiar test in Hollywood. Audiences can become easily bored with the same comedic or dramatic character if he or she continually resurfaces in different films. An actor who can successfully embody a range of dramatic, comedic and action roles will have more parts to choose from and more fans to bring into the theaters.

"The question is whether an actor has consistent box-office draw from film to film," says Bock. "Ultimately, that's the mark of a successful and long career."

One actor who carries both comedic and action roles is Shia LaBeouf, No. 10 on our list. LaBeouf rose from Disney Channel fame, where he portrayed lighthearted Louis Stevens on Even Stevens, to action flick front-runner in just four years. LaBeouf's films "Transformers," "Indiana Jones and the Kingdom of the Crystal Skull" and "Eagle Eye" were included in his total of six starring roles in the last four years, with a cumulative total of $952 million.

Most of the stars that made this list -- including Mark Wahlberg, Johnny Depp, Scarlett Johansson and Will Ferrell -- portray a limited range of on-screen characters. They bring something to the screen that risk-averse Hollywood is willing to put its money behind: consistent box-office draw. "It's always been a star-driven product. That's the bottom line," says Bock.